Pharmaceutical administration form for peptides, process for its preparation, and use

ABSTRACT

A method for preventing aggregation of an LHRH antagonist in a pharmaceutical composition. The method comprises combining the LHRH antagonist in the form of an acetate, gluconate, glucuronate, lactate, citrate, ascorbate, benzoate or phosphate salt and at least one of the acids for forming the salts in free acid form.

This is a divisional application of application Ser. No. 09/861,009 filed on May 18, 2001, which is incorporated herein by reference in its entirety.

The invention relates to novel galenic forms for the parenteral administration of peptides prone to aggregation, in particular of LHRH analogues or LHRH antagonists and agonists, and processes for their preparation, and use.

EP 0 299 402 discloses the use of pharmaceutically active decapeptides such as SB-030, SB-075 (cetrorelix) and SB-088 in the form of their pharmaceutically acceptable, non-toxic acid addition salts such as hydrochlorides, hydrobromides, sulphates, phosphates, fumarates, gluconates, tannates, maleates, acetates, citrates, benzoates, succinates, alginates, pamoates, ascorbates and tartrates etc.

JP 06321800-A furthermore discloses a lyophilized peptide or protein preparation which contains gluconate salts as stabilizers. In one example, the solution contains 2.5% of magnesium gluconate, the active compounds described being, inter alia, vasopressin, LHRH and insulin.

It is known from the literature, inter alia from Powell, M. F., Pharmaceutical Research, 1258-1263(8) 1991; Dathe M. Int. J. Peptide Protein Res. 344-349(36) 1990, and Szejtli, J. Pharmaceutical Technology International 16-22, 1991, that oligopeptides, namely particularly those having a terminal acid amide function, are prone to gel formation.

EP 0 611 572 describes a preparation process for a lyophilizate of a peptide having 3-15 amino acids, according to which 100-10,000 parts by weight of the peptide are dissolved in acetic acid and treated with bulking agents such as mannitol, and then lyophilized in order to obtain a sterile-filtered lyophilizate of the peptide and to avoid gel formation.

DE A 195 42 873 describes pharmaceutical administration forms of complicated composition in the form of microparticles, according to which an ABA triblock copolymer is used whose A block is a polymer of milk [sic] and glycolic acid and whose B polymer is a polyethylene glycol chain, together with an additive from the group consisting of the serum proteins, polyamino acids, cyclodextrins, cyclodextrin derivatives, saccharides, amino sugars, amino acids, detergents or carboxylic acids and mixtures of these substances. After inclusion of small or aggregation-sensitive amounts of polypeptide, the microparticles described should also release the polypeptide continuously over a relatively long period.

DD 141 996 describes the preparation of pharmaceutical forms of native LHRH which are stable over a relatively long period and comply with the requirements for a parenterally administerable preparation. The key point here is the improvement in the shelf life of these preparations (page 2, lines 19-23). No statement is made about the filterability of the solutions. Moreover, to improve the shelf life buffer substances (also acetic acid) are also employed to establish a pH range of pH 3.5-6.5. The problem of preparing sterile lyophilizates from gel-forming peptide salts is not solved there.

EP 0 175 506 treats an aqueous solution of the peptide with 1N acetic acid and then lyophilizes it in order to obtain the acetate salt of the peptide. The subject of this application is thus the synthesis of the peptide salts.

However, it has been shown that in the case of the known acetate salts of the peptides prone to aggregation, such as the LHRH antagonists, the preparation of sterile solutions for parenteral administration by means of filtration, especially at high concentrations, is indeed possible, but aggregates can form shortly before injection after the dissolution of the lyophilizate. The aggregates then lead to a concentration-dependent lowering of the bioavailability from a peptide concentration of 0.5 mg/ml.

The problem mentioned occurs not only with injection solutions which are administered for the purpose of rapid release of active compound, but is also observed with injection preparations which exhibit delayed release. Thus peptides, incorporated in matrices which should control the release of active compound, can have an undesirably low release on account of their proneness to aggregation. Thus the bioavailability is also lowered here.

Starting from the fact that the preferred administration of pharmaceutically active peptides such as LHRH agonists and antagonists, for example antarelix and cetrorelix, is the parenteral pharmaceutical form, a need exists for the provision of stable injection preparations having acceptable bioavailability, which can be conveniently prepared, sterile-filtered and formulated. This applies in particular to injection preparations in the form of reconstituted lyophilizates of soluble peptide salts and to microparticles, microcapsules or implants.

This is all the more of importance in consideration of the varied areas of use of the LHRH antagonists, which are becoming more and more known.

A wider selection of parenterally, in particular subcutaneously, injectable, stable peptide solutions is desirable in view of the rapidly growing indication areas of this class of substance.

Pharmaceutical administration forms suitable for parenteral administration, which contain peptides prone to aggregation in dissolved or dispersed form, have now been developed which are distinguished in that the peptides are present in the form of their acetate, gluconate, glucuronate, lactate, citrates, ascorbate, benzoate or phosphate salts and that these administration forms can additionally contain one of the just-mentioned acids as free acids, and, if appropriate, further additives and excipients from the class consisting of the acids, surface-active substances, polymers, lipids or sugars.

These pharmaceutical administration forms can be present in dissolved or dispersed form in water or in aqueous solvent mixtures.

According to a further embodiment of the invention, the pharmaceutical administration forms can also be present in dissolved or dispersed form in a physiologically tolerable oil, preferably medium-chain triglycerides (neutral oils, Miglyol®) or castor oil, sesame oil, cottonseed oil, maize oil, peanut oil, olive oil or in mixtures of such oils.

The peptides employed are the LHRH antagonists antide, A-75998, ganirelix and Nal-Glu antagonist, but in particular cetrorelix, antarelix and the antagonists according to the Patents U.S. Pat. No. 5,942,493 and DE 19911771.3.

Acids employed in the excipient function are gluconic acid, glucuronic acid, galacturonic acid, glucaric acid, citric acid, ascorbic acid and amino acids.

It is thus possible to suppress the aggregation of the peptide and thus to fulfil the requirements for a preparation having good bioavailability, and thus to enrich the pharmaceutical wealth and to do so with efficient galenic technology.

It has further surprisingly been found that by the addition of gluconic, glucuronic, citric, lactic or ascorbic acid, the stability of various cetrorelix salts is moreover considerably improved.

According to the invention, the preparation and formulation of sterile-filtered, stable preparations is thus possible without problems.

It is additionally advantageous to add suitable excipients. These excipients can be acids, surface-active substances, polymers, lipids or sugars. Examples of acids are gluconic acid, glucuronic acid, galacturonic acid, glucaric acid, lactic and citric acid, ascorbic acid and amino acids. Surface-active substances employed can be polyethylene glycol 12-(hydroxy)stearate (Solutol®), polyoxyethylene ricinoleate (Cremophor®), polysorbates, poloxamers, phospholipids, lecithins or benzalkonium chloride. Suitable polymers are albumins, polyethylene glycols, cellulose derivatives, starch derivatives or polyvinylpyrrolidone. Examples of sugars are cyclodextrins and cyclodextrin derivatives. ‘Chaotropic’ substances such as urea can also serve as additives and/or excipients.

The area of use of the preparations according to the invention is in particular in the prevention and therapy of all sex hormone-dependent conditions and diseases which can be influenced by LHRH analogues, i.e. LHRH agonists and LHRH antagonists. Those to be emphasized here are:

-   -   benign prostate hyperplasia, carcinoma of the prostate,         precocious puberty, hirsutism, endometrial hyperplasia and its         accompanying symptoms, endometrial carcinoma, in-vitro         fertilization (IVF/COS/ART), contraception, premenstrual         syndrome (PMS), uterine myomatosis, breast cancer, tubal         obstruction (PTO), ovarian cancer, carcinoma of the uterus. The         following substances are particularly preferred as LHRH         antagonists for the composition according to the invention:     -   cetrorelix, antarelix, antide, A-75998, ganirelix, the Nal-Glu         antagonist, and LHRH antagonists according to the Patents U.S.         Pat. No. 5,942,493 and DE 19911771.3.

The LHRH antagonists according to the Patents U.S Pat. No.5,942,493 and DE 19911771.3 are compounds of the following general formulas I, V and VII and the salts thereof with pharmaceutically acceptable acids

in which n is the number 3 or 4, R¹ is an alkyl group, an alkyloxy group, an aryl group, a heteroaryl group, an aralkyl group, a heteroaralkyl group, an aralkyloxy group or a heteroaralkyloxy group, in each case unsubstituted or substituted, R² and R³ independently of one another are each a hydrogen atom, an alkyl group, an aralkyl group or a heteroaralkyl group, in each case unsubstituted or substituted, where the substitution can in turn consist of an aryl group or heteroaryl group, or —NR²R³ is an amino acid group, and R⁴ is a group having the formula (II) —(CH₂)_(p)—CO—NR⁵R⁶  (II) in which p is an integer from 1 to 4, R⁵ is hydrogen or an alkyl group and R⁶ is an unsubstituted or substituted aryl or heteroararyl group,

-   -   or R⁴ is a ring of the general formula (III)

in which q is the number 1 or 2, R⁷ is a hydrogen atom or an alkyl group, R⁸ is a hydrogen atom or an alkyl group and X is an oxygen or sulphur atom, where the aromatic or heteroaromatic radicals can be partially or completely hydrogenated and chiral carbon atoms can have the R- or S-configuration, and its salts with pharmaceutically acceptable acids; Ac-D-Nal(2)¹-D-(pCl)Phe²-D-Pal(3)³-Ser⁴-Tyr⁵-D-Xxx⁶-Leu⁷-Arg⁸-Pro⁹-D-Ala¹⁰-NH₂  (V) in which D-Xxx is an amino acid group of the general formula (VI)

in which n is the number 3 or 4, R⁴ is a group of the formula (II)

in which p is an integer from 1 to 4, R⁵ is hydrogen or an alkyl group and R⁶ is an unsubstituted or substituted aryl group or heteroaryl group, or R⁴ is a ring of the general formula (III)

in which q is the number 1 or 2, R⁷ is a hydrogen atom or an alkyl group, R⁸ is a hydrogen atom or an alkyl group and X is an oxygen or sulphur atom, and its salts with pharmaceutically acceptable acids; and A-Xxx¹-Xxx²-Xxx³-Xxx⁴-Xxx⁵-Xxx⁶-Xxx⁷-Xxx⁸-Xxx⁹-Xxx¹⁰-NH₂  (VII) in which

-   A is an acetyl or a 3-(4-fluorophenyl)propionyl group, -   Xxx¹ is D-Nal(1) or D-Nal(2), -   Xxx²-Xxx³ is D-Cpa-D-Pal(3) or a single bond, -   Xxx⁴ is Ser, -   Xxx⁵ is N-Me-Tyr, -   Xxx⁶ is D-Cit, D-Hci or a D-amino acid group of the general formula     (VIII)

in which n is the number 3 or 4, where R¹¹ is a group having the general formula (IX) —(CH₂)_(p)—CO—NR¹²R¹³  (IX) where p is an integer from 1 to 4, R¹² is hydrogen or an alkyl group and R¹³ is an unsubstituted or substituted aryl group or heteroaryl group, or R¹¹ is a 3-amino-1,2,4-triazole-5-carbonyl group or R¹¹ is a ring of the general formula (X)

in which q is the number 1 or 2, R¹⁴ is a hydrogen atom or an alkyl group, R¹⁵ is a hydrogen atom or an alkyl group and X is an oxygen or sulphur atom,

-   Xxx⁷ is Leu or Nle, -   Xxx⁸ is Arg or Lys(iPr), -   Xxx⁹ is Pro and -   Xxx¹⁰ is Ala or Sar,     and their salts with pharmaceutically acceptable acids.

EXAMPLE 1

By means of polarization microscopy, aggregation investigations were carried out on solutions of various cetrorelix salts without or with addition of excipients.

In the polarization light microscope with crossed polarizers, aggregated peptide solutions show images which are very similar to those of liquid-crystalline structures. In contrast to this, aggregate-free peptide solutions produce no such effects.

TABLE 1 Influence of a gluconic acid addition on the aggregation behaviour of cetrorelix acetate solutions. Gluconic acid Concentration in the of cetrorelix reconstitution Days without acetate, mg/ml medium, %: pH aggregation 2.5 0 4.7 1 2.5 0.0071 4.5 2 2.5 0.071 3.7 2 2.5 0.71 3.1 12

Thus the addition of gluconic acid causes an improvement in the stability of cetrorelix acetate solutions by delaying or preventing aggregation.

Further experiments concentrated on cetrorelix gluconate without or with addition of gluconic acid. The most important results are summarized in Table 2.

TABLE 2 Aggregation behaviour of various solutions which were prepared from cetrorelix gluconate bulk material. Gluconic acid addition: Concentration Yes No of Days Days cetrorelix, without without mg/ml pH aggregation pH aggregation 2.5 3.0 >30 5 3.6 4 4.8 1 5 3.8 4 4.7 1 7.5 3.4 1 4.7 0 7.5 3.7 1 4.8 0

Cetrorelix gluconate thus offers advantages in comparison with the acetate salt. The addition of gluconic acid increases the shelf life of cetrorelix gluconate solutions.

Moreover, the stabilizing influence of glucuronic acid on cetrorelix acetate solutions and, as a further salt, also cetrorelix glucuronate, was tested for its aggregation behaviour. The results are summarized in Table 3.

TABLE 3 Aggregation behaviour of variously concentrated solutions of cetrorelix acetate and cetrorelix glucuronate without or with addition of glucuronic acid. Glucuronic acid addition: Concentration Yes No of Days Days cetrorelix, without without Salt form mg/ml pH aggregation pH aggregation Acetate 2.5 3.0 >21 4.7 0 Acetate 5 3.0 0 Glucuronate 2.5 2.9 >30 4.5 3 Glucuronate 5 2.7 >30 4.6 0

Also, by the replacement of the acetate salt by a glucuronate salt, significant improvements can be achieved with respect to the aggregation stability of cetrorelix similarly to with the gluconate salt. By the addition of glucuronic acid to cetrorelix glucuronate solutions, the aggregation stability of these solutions can be even further improved.

TABLE 4 Aggregation-free duration in days of cetrorelix acetate solutions after addition of 10% of α-cyclodextrin, 20% of hydroxypropyl-β-cyclodextrin or 20% of γ-cyclodextrin. Concen- tration of cetrorelix acetate, Hydroxypropyl- mg/ml α-Cyclodextrin β-cyclodextrin γ-Cyclodextrin 2.5 7 24 98 + (168, 182, 189) 5 0 7 31 + (140, 147, 182) 7.5 0 10  5 + (20, 20, 20) 10 0 2  2 + (4, 4, 4) 15 0  0

By the addition of hydroxypropyl-β-cyclodextrin and particularly of γ-cyclodextrin, the aggregation stability of cetrorelix acetate solutions can be significantly improved.

TABLE 5 Aggregation-free duration in days of 2.5 mg/ml cetrorelix gluconate solutions after addition of α-cyclodextrin, hydroxypropyl-β-cyclodextrin or γ-cyclodextrin. Concentration of Days without Cyclodextrin type cyclodextrin, % aggregation γ-Cyclodextrin 20 182 6.8 126 Hydroxypropyl-β-cyclodextrin 20 189 6.8 91 α-Cyclodextrin 10 140 5 1

By the addition of hydroxypropyl-β-cyclodextrin or of γ-cyclodextrin, the aggregation stability of cetrorelix gluconate solutions can also be significantly improved.

TABLE 6 Aggregation-free duration in days of cetrorelix acetate solutions with addition of polyvinylpyrrolidone (Kollidon ® 12 PF or 17 PF). Concentration Days without Days without of aggregation aggregation cetrorelix, Concentration with Kollidon ® with Kollidon ® mg/ml of Kollidon ®, % 12 PF 17 PF 2.5 0 0 0 5 1 2 10 1 2 15 77 63 20 84 98 5 15 0 1 20 0 1

Also, by the addition of various types of polyvinylpyrrolidone, the aggregation stability of cetrorelix acetate solutions can be significantly improved.

TABLE 7 Aggregation behaviour of cetrorelix acetate solutions with addition of various excipients assessed by means of polarization microscopy and according to the optical appearance. Conc. of Conc. of Aggregation Excipient excipient cetrorelix (microscopy) Appearance Solutol ®  5.00% 2.5 mg/ml yes, after clear HS 15 14 days solution 10.00% 2.5 mg/ml ≧112 days clear without solution aggregation 20.00% 2.5 mg/ml ≧112 days clear without solution aggregation Cremophor ®  5.00% 2.5 mg/ml yes, after clear EL 10 days solution 10.00% 2.5 mg/ml ≧112 days clear without solution aggregation 20.00% 2.5 mg/ml ≧112 days clear without solution aggregation 20.00%   5 mg/ml yes, after 1 clear, day viscose L-glutamic  0.80% 2.5 mg/ml yes, after 2 clear acid days solution, pH 3.8 Glucaric  2.50% 2.5 mg/ml ≧12 days clear acid without solution, aggregation pH 2.5 Galacturonic  2.50% 2.5 mg/ml ≧12 days clear acid without solution, aggregation pH 2.6

EXAMPLE 2

Cetrorelix bulk material is dissolved in a concentration of 10 mg/ml in 30% strength acetic acid and diluted with an aqueous solution of the additives to a final concentration of 1 mg/ml of peptide in 3% acetic acid. This solution is then sterile-filtered and lyophilized (5 mg per vial).

After reconstitution of these lyophilizates, the solutions (2.5 mg/ml of cetrorelix) are investgated in the following tests for aggregate formation and release behaviour:

-   -   Polarization microscopy (pol. mic.): days without aggregation.     -   Filterability in %:     -   Cetrorelix solutions are prepared according to a standardized         procedure and filtered through 0.22 μm or 0.45 μm filters by         means of centrifugation. The concentration of cetrorelix in the         filtrate is determined by HPLC and indicated as a % value, based         on the starting concentration before filtration (filterability         in %).     -   in-vitro release form (RRS, release in Ringer's solution):     -   % released after 1 h and after 6 h.     -   The in-vitro release behaviour is determined at 37° C. in a flow         procedure using Ringer's solution as medium. The concentration         measurement is carried out by HPLC. Cetrorelix samples,         corresponding to 10 mg of cetrorelix base, are weighed into the         flow cell, mixed with 4 ml of water and stirred for 10 min.         After addition of 6 ml of Ringer's solution to the sample,         Ringer's solution is pumped uniformly through the flow cell with         a flow of 0.5 ml/min, with stirring.     -   Rat animal experiment: cetrorelix residual content in the muscle         in % of the administered dose 168 h after injection.

Some prepared batches of cetrorelix acetate lyophilizate and the corresponding test results of 2.5 mg/ml cetrorelix acetate solutions prepared therefrom are shown in Table 8a.

TABLE 8a Batches of cetrorelix Pol. mic., RRS, Rat % acetate lyophilizate days 0.22 μm [%] i.m. (5 mg) . . . without filterable after after Excipients aggr. [%] 1 h 6 h 168 h only mannitol 0 about (=control) 55 Solutol ®/mannitol 48 100 Cremophor ®/mannitol 46 101 Solutol ®/alanine 16 98 17 24 Solutol ®/alanine/ 19 101 57 68 5.7 gluconic acid Solutol ®/mannitol/ >45 100 84 88 3.8 gluconic acid Cremophor ®/mannitol/ >45 101 gluconic acid Solutol ®/tryptophan/ imposs. mannitol Solutol ®/tryptophan/ 6 9.6 gluconic acid Cyclodextrin molar 2 101 16 27 10 ratio 1:10/mannitol Cyclodextrin molar >45 102 68 74 ratio 1:10/mannitol/ gluconic acid Cyclodextrin molar 17 100 68 76 ratio 1:30/mannitol Cyclodextrin molar 5 101 39 52 6.3 ratio 1:10/alanine/ gluconic acid Mannitol/citric acid 1 102 45 53 Solutol ®/mannitol/ >36 100 84 91 7.4 citric acid Solutol ®/alanine/ 1 99 47 54 citric acid Solutol ®/glycine >36 97 24 31 Solutol ®/urea 21 100 32 40 Solutol ®/glycine/ >36 99 82 89 gluconic acid Solutol ®/urea/gluconic >36 100 acid Cremophor ®/alanine/ (36) gluconic acid Cremophor ®/urea/ (36) gluconic acid Pluronic ® F127/mannitol 1 5% Tween ® 80/mannitol >16 Polyethylene glycol 1 4000/mannitol Dextran/mannitol 1 Phenylmercury 2 acetate/mannitol

In the examples shown, it is evident that with a large number of the tested excipients from various groups of substances (surface-active substances, acids, amino acids, polymers, sugars, sugar alcohols, cyclodextrins, preservatives), stabilizing effects can be achieved in vitro (polarization microscopy, filterability, in-vitro release) and in vivo individually or with mixtures of these excipients. This reduced tendency to aggregate and thus improved in-vitro release of active compound also leads in the rat experiment to improved bioavailabilities of the peptide active compound and thus to reduced residual contents in the rat muscle.

Further in-vitro and in-vivo data of batches containing various cetrorelix salts without or with addition of stabilizing excipients are listed in Table 8b which follows:

TABLE 8b Cetrorelix salts Conc. of Pol. mic Rat % (reconstituted with cetrorelix days RRS, [%] i.m. water) from lyo without after after Excipients mg/ml aggr. 1 h 6 h 168 h Acetate 2.5 0 12 24.5 about 55 Acetate 2.5 0 13 35.9 about 55 Acetate 5 0 10 35 Acetate reconstituted 2.5 18 50 63.2 15.2 with gluconic acid Acetate + Kollidon ® 2.5 84 15 43.4 20.2 12 PF Acetate + Kollidon ® 2.5 98 22 50.6 17 PF Acetate + benzalkonium 2.5 6.3 30.3 chloride Acetate + phospholipids 2.5 7.3 23.3 Acetate + γ- 2.5 22.6 44.5 10 cyclodextrin (1:10) Acetate + γ- 2.5 28 56.7 cyclodextrin (1:30) Acetate + γ- 2.5 35.1 56.6 cyclodextrin (1:50) Acetate + γ- 2.5 >168 34.5 60.2 3.6 cyclodextrin (1:90) Acetate + γ- 5 140 19 47.8 cyclodextrin (1:90) Acetate + γ- 7.5 20 cyclodextrin (1:90) Acetate + γ- 10 4 45.2 cyclodextrin (1:90) Acetate reconstituted 15 49.1 with gluconic acid Gluconate 2.5 18 45.3 Gluconate 2.5 11.3 46 Gluconate 2.5 77.5 83.6 reconstituted with gluconic acid Citrate 15 9 20.3 Lactate bulk 20 55.2 Embonate 15 13 43

EXAMPLE 3

Cetrorelix formulations which are less prone/slower to aggregate (better filterability/polarization microscopy) and exhibit more rapid in-vitro release in Ringer's solution precipitate after 168 h in the rat muscle experiment owing to their lower residual content of cetrorelix. A higher bioavailability is expected of such formulations.

Some results of rat muscle experiments have already been listed in Tables 8a and 8b.

In the further rat muscle experiments shown in Table 9, in addition to the residual content in the muscle, the cetrorelix content in the plasma was additionally determined. With the aid of these data too, the stabilizing influence of the excipients tested is clear.

Moreover, it was possible by the replacement of the acetate salt by other salt forms of cetrorelix to achieve an improved bioavailability and, accompanying this, a reduced residual amount in the rat muscle experiment.

TABLE 9 Cetrorelix Cetrorelix Cetrorelix concentra- content in content in tion of the the muscle the plasma, Substance Dose inj. soln (168 h), % % of the (cetrorelix) (mg/kg) (mg/ml) of the dose dose Acetate + Solutol ® + 1.5 2.5 5.7 alanine + gluconic acid Acetate + Solutol ® + 1.5 2.5 9.6 tryptophan + gluconic acid Acetate + cyclodextrin 1.5 2.5 10.0 83.4 1:10 Acetate + cyclodextrin 1.5 2.5 6.3 81.8 1:10, alanine, gluconic acid Acetate + Solutol ® + 1.5 2.5 3.8 gluconic acid Acetate + Solutol ® + 1.5 2.5 7.4 citric acid Acetate 1.5 3 55.1 92.2 Acetate in Miglyol ® 1.5 3 22.3 74.2 Acetate + 1.5 3 76.9 39.8 benzalkonium chloride Acetate + 20% 1.5 3 3.6 106.2 cyclodextrin Acetate + 20% 1.5 3 20.2 88.4 Kollidon ® Acetate + glucuronic 1.5 3 23.6 106.1 acid Acetate + gluconic 1.5 3 15.2 95.5 acid Acetate + 20% 3.0 10 45.2 60.9 cyclodextrin Acetate 3.0 15 56.5 28.7 Acetate in Miglyol ® 3.0 15 24.2 57.2 Acetate + 0.025% 3.0 15 10.5 21.4 benzalkon. Acetate + glucuronic 3.0 15 78.1 43.8 acid Acetate + gluconic 3.0 15 49.1 45.5 acid Gluconate 1.5 15 37.9 46.9 Gluconate in mannitol 1.5 3 24.6 58.0 Gluconate in mannitol 1.5 3 25.4 75.2 Gluconate in 1.5 3 28.8 46.3 Miglyol ® Gluconate in 1.5 3 13.2 120.0 gluconic acid Gluconate in 3.0 15 29.2 gluconic acid Gluconate in 3.0 15 43.5 74.2 gluconic acid Glucuronate 1.5 3 16.5 78.6 Glucuronate 3.0 15 18.8 Lactate 3.0 15 33.2 72.1 Lactate 1.5 3 30.7 67.1 Citrate lyo/a 1.5 3 22.8 36.6 Citrate in Miglyol ® 1.5 3 14.8 53.1 Base 1.5 3 27.2 122.2 Base in Miglyol ® 1.5 3 38.9 55.9 Benzoate in mannitol 1.5 3 34.2 32.7 Benzoate in 1.5 3 33.1 21.1 Miglyol ® Phosphate 1.5 3 32.9 22.6 

1. A method for suppressing aggregation of the LHRH antagonist salt cetrorelix acetate in a pharmaceutical composition for parenteral administration, comprising the steps of: providing a pharmaceutically effective amount of cetrorelix acetate, in a concentration of 2.5 mg/ml total solution; dissolving or dispersing cetrorelix acetate in a carrier; and including in said carrier a pharmaceutically acceptable acid and % in total solution thereof, selected from the group consisting of gluconic acid of at least 0.0071%, or glucaric acid or galacturonic acid of 2.5%, wherein the pharmaceutically acceptable acid is present as free acid and is in an amount capable of imparting a pH of 2.5 to 4.5 to the composition and suppressing aggregation of cetrorelix acetate.
 2. The method of claim 1, wherein said carrier is water, physiologically tolerable oil, or an aqueous solvent mixture.
 3. The method of claim 1, further comprising adding an excipient.
 4. The method of claim 3, wherein said excipient is selected from the group consisting of gluconic acid, glucuronic acid, galacturonic acid, glucaric acid, citric acid, ascorbic acid, an amino acid, polyethylene glycol 12-(hydroxy)stearate, polyoxyethylene ricinolcate, polysorbates, poloxamers, phospholipids, lecithins, a preservative, albumins, polyethylene glycols, cellulose derivatives, starch derivatives, polyvinylpyrrolidone, cyclodextrins or its derivatives, sugar alcohols, urea, chaotropic substances, and mixtures thereof.
 5. The method of claim 1, further comprising incorporating a polymer to delay the release of cetrorelix acetate.
 6. The method of claim 5, wherein said polymer is a homo- or copolymer of lactic or glycolic acid.
 7. The method of claim 2, wherein said oil is a medium-chain triglyceride oil, castor oil, sesame oil, cottonseed oil, maize oil, peanut oil, olive oil, or mixtures thereof.
 8. The method of claim 1, wherein said pharmaceutical composition is an injection preparation.
 9. The method of claim 1, wherein said carrier is water and wherein said pharmaceutically acceptable acid is independently selected from glucaric acid or galacturonic acid.
 10. A method for preparing a pharmaceutical composition for parenteral administration, comprising a pharmaceutically effective amount of the LHRH antagonist salt cetrorelix acetate dissolved or dispersed in a carrier, comprising: providing a pharmaceutically effective amount of cetrorelix acetate, in a concentration of 2.5 mg/ml total solution; subjecting cetrorelix acetate to double decomposition with a pharmaceutically acceptable acid and % in total solution thereof, selected from the group consisting of gluconic acid of at least 0.0071%, or glucaric acid or galacturonic acid of 2.5%, wherein the pharmaceutically acceptable acid is present as free acid and is in an amount capable of imparting a pH of 2.5 to 4.5 to the composition and suppressing aggregation of cetrorelix acetate, to produce a corresponding cetrorelix acetate in a stoichiometric ratio; dissolving cetrorelix acetate in water to form a solution; sterile-filtering said solution to form a sterile-filtered solution; dispensing said sterile-filtered solution into at least one vial; lyophilizing said sterile-filtered material in said at least one vial to form a lyophilisate; and reconstituting said lyophilisate with a carrier before the parenteral administration.
 11. The method of claim 10, wherein said carrier is water, physiologically tolerable oil, or an aqueous solvent mixture.
 12. The method of claim 10, further comprising adding an excipient.
 13. The method of claim 12, wherein said excipient is selected from the group consisting of gluconic acid, glucuronic acid, galacturonic acid, glucaric acid, citric acid, ascorbic acid, an amino acid, polyethylene glycol 12-(hydroxy)stearate, polyoxyethylene ricinolcate, polysorbates, poloxamers, phospholipids, lecithins, a preservative, albumins, polyethylene glycols, cellulose derivatives, starch derivatives, polyvinylpyrrolidone, cyclodextrins or its derivatives, sugar alcohols, urea, chaotropic substances, and mixtures thereof.
 14. The method of claim 10, further comprising incorporating a polymer to delay the release of said LHRH antagonist.
 15. The method of claim 14, wherein said polymer is a homo- or copolymer of lactic or glycolic acid.
 16. The method of claim 11, wherein said oil is a medium-chain triglyceride oil, castor oil, sesame oil, cottonseed oil, maize oil, peanut oil, olive oil, or mixtures thereof.
 17. The method of claim 10, wherein said pharmaceutically acceptable acid is independently selected from glucaric acid or galacturonic acid.
 18. The method of claim 10, wherein said vial is an injection vial. 